Hapten-induced colitis is associated with colonic patch hypertrophy and T helper cell 2-type responses.
(9/1614)
To investigate the potential involvement of T helper (Th)2-type responses in murine models of intestinal inflammation, we used trinitrobenzene sulfonic acid (TNBS)-hapten to induce inflammatory bowel disease in situations where Th1-type responses with interferon (IFN)-gamma synthesis are either diminished or do not occur. Intracolonic administration of TNBS to either normal (IFN-gamma+/+) or Th1-deficient IFN-gamma knockout (IFN-gamma-/-) BALB/c mice resulted in significant colitis. In IFN-gamma-/- mice, crypt inflammation was more severe than in IFN-gamma+/+ mice and was accompanied by hypertrophy of colonic patches with a lymphoepithelium containing M cells and distinct B and T cell zones resembling Peyer's patches. Hapten-specific, colonic patch T cells from both mouse groups exhibited a Th2 phenotype with interleukin (IL)-4 and IL-5 production. TNBS colitis in normal mice treated with anti-IL-4 antibodies or in IL-4(-/-) mice was less severe than in either IFN-gamma+/+ or IFN-gamma-/- mice. Our findings now show that the Th2-type responses in TNBS colitis are associated with colonic patch enlargement and inflammation of the mucosal layer and may represent a model for ulcerative colitis. (+info)
Regulation of the human interleukin-5 promoter by Ets transcription factors. Ets1 and Ets2, but not Elf-1, cooperate with GATA3 and HTLV-I Tax1.
(10/1614)
Interleukin-5 (IL-5), expressed primarily by type-2 T helper (Th2) cells, plays an important role in the development of allergic diseases, such as allergic asthma. Studying the regulation of IL-5 gene expression by Ets transcription factors, we found that Ets1 and Ets2, but not Elf-1, were able to activate the human IL-5 promoter in Jurkat T-cells. This required the presence of either phorbol 12-myristate acetate (PMA) plus ionomycin or PMA plus the viral protein HTLV-I Tax1. By mutation studies, it could be shown that Ets1 and Ets2 exerted their effects on the IL-5 promoter through a GGAA motif within the Cle0 element. In myeloid Kasumi cells, Ets1 and Ets2 failed to stimulate IL-5 promoter activity, unless the T-cell specific transcription factor GATA3 was added. These results show, for the first time, that Ets1 and Ets2 are able to cooperate with GATA3. Both ionomycin and Tax1 increased the combined effect of GATA3 with Ets1 and Ets2 in the presence of PMA. The data further demonstrate that, in addition to Ets1, Ets2 is also able to functionally cooperate with Tax1. The synergism of GATA3 with either Ets1 or Ets2 may play an important role in calcium- or Tax1-dependent regulation of IL-5 expression in Th2 cells or in HTLV-I transformed adult T-cell leukemia cells, respectively. (+info)
Vitamin A prevents the decline in immunoglobulin A and Th2 cytokine levels in small intestinal mucosa of protein-malnourished mice.
(11/1614)
We examined whether vitamin A improved mucosal immune depression in mice with wasting protein deficiency. In male C3H/HeN mice fed a semi-purified 1% protein diet for 2 wk, plasma retinol and immunoglobulin A (IgA) concentrations in the small intestinal mucosa were 50 and 55%, respectively, of those in mice fed a semi-purified 20% protein diet, (P < 0.05). Daily supplementation of 0.3 mg of retinyl acetate to protein-deficient mice for 2 wk increased the plasma retinol level to the value in the protein-sufficient mice. However, 1 mg/d of retinyl acetate was required to prevent the decline of the IgA level caused by the protein deficiency. Mice fed the low-protein diet had lower concentrations of IL-4 and IL-5 in the small intestinal mucosa and fewer IL-4- and IL-5-containing cells in the lamina propria (P < 0. 05). Retinyl acetate (1 mg) significantly restored the IL-5 level and the number of IL-4- and IL-5-containing cells. After immunization with 20 microg of cholera toxin (CT), the intestinal mucosa of protein-deficient mice contained significantly less CT-specific IgA than control mice. Treatment with 1 mg of retinyl acetate prevented the decline of anti-CT IgA level in the protein-deficient mice, improving their survival rate after an exposure to 0.1 mg of CT. These results suggest that large oral supplements of vitamin A may preserve mucosal IgA level during protein malnutrition, possibly by stimulating Th2 cytokine production and thereby, inducing resistance against infection. (+info)
Interleukin 9-induced in vivo expansion of the B-1 lymphocyte population.
(12/1614)
The activity of interleukin (IL)-9 on B cells was analyzed in vivo using transgenic mice that constitutively express this cytokine. These mice show an increase in both baseline and antigen-specific immunoglobulin concentrations for all isotypes tested. Analysis of B cell populations showed a specific expansion of Mac-1(+) B-1 cells in the peritoneal and pleuropericardial cavities, and in the blood of IL-9 transgenic mice. In normal mice, the IL-9 receptor was found to be expressed by CD5(+) as well as CD5(-) B-1 cells, and repeated injections of IL-9 resulted in accumulation of B-1 cells in the peritoneal cavity, as observed in transgenic animals. Unlike other mouse models, such as IL-5 transgenic mice, in which expansion of the B-1 population is associated with high levels of autoantibodies, IL-9 did not stimulate the production of autoantibodies in vivo, and most of the expanded cells were found to belong to the B-1b subset (IgM+Mac-1(+)CD5(-)). In addition, we found that these IL-9-expanded B-1b cells do not share the well-documented antibromelain-treated red blood cell specificity of CD5(+) B-1a cells. The increase of antigen-specific antibody concentration in immunized mice suggests that these B-1 cells are directly or indirectly involved in antibody responses in IL-9 transgenic mice. (+info)
An adoptive transfer model of allergic lung inflammation in mice is mediated by CD4+CD62LlowCD25+ T cells.
(13/1614)
Animal models of allergic lung inflammation have provided important insight into the cellular and biochemical factors involved in the pathogenesis of human asthma. Herein, we describe an adoptive transfer model of OVA-specific eosinophilic lung inflammation in the mouse that is used to characterize the cells involved in mediating the pulmonary inflammatory response. We report that freshly isolated spleen cells from OVA-sensitized mice are unable to prime naive recipient mice to respond to a subsequent OVA aerosol challenge. Subjecting the spleen cells to short term restimulation with Ag in vitro, however, renders the cells competent to transfer activity. The magnitude and the kinetics of the eosinophilic pulmonary inflammation in the adoptive transfer recipients are nearly identical with those generated by a more conventional active sensitization/challenge protocol, with the notable exception of differential production of plasma IgE in the two models. Extensive negative and positive selection of splenocyte subtypes indicates that the transfer of Ag-primed CD4+ T cells is both necessary and sufficient to establish full responsiveness in the recipient mice. Additional phenotypic characterization of the transfer-reactive CD4+ T cells indicates that they are found within the CD62LlowCD25+ subset and secrete high levels of IL-5 in response to Ag stimulation. Limiting dilution analysis-derived minimal frequency estimates indicate that approximately 1 in 8500 of the sensitized, cultured spleen cells produces IL-5 in response to OVA stimulation in vitro, suggesting that eosinophilic lung inflammation can be induced in naive mice by the transfer of <1200 Ag-specific CD4+ T cells. (+info)
Th2-induced airway mucus production is dependent on IL-4Ralpha, but not on eosinophils.
(14/1614)
Mucus hyperproduction in asthma results from airway inflammation and contributes to clinical symptoms, airway obstruction, and mortality. In human asthmatics and in animal models, excess mucus production correlates with airway eosinophilia. We previously described a system in which TCR transgenic CD4 Th2 cells generated in vitro were transferred into recipient mice and activated in the respiratory tract with inhaled Ag. Th2 cells stimulated airway eosinophilia and a marked increase in mucus production, while mice that received Th1 cells exhibited airway inflammation without eosinophilia or mucus. Mucus could be induced by IL-4-/- Th2 cells at comparable levels to mucus induced by IL-4+/+ Th2 cells. In the current studies we dissect further the mechanisms of Th2-induced mucus production. When IL-4-/- Th2 cells are transferred into IL-4Ralpha-/- mice, mucus is not induced, and BAL eosinophilia is absent. These data suggest that in the absence of IL-4, IL-13 may be critical for Th2-induced mucus production and eosinophilia. To determine whether eosinophils are important in mucus production, IL-5-/- Th2 cells were transferred into IL-5-/- recipients. Eosinophilia was abolished, yet mucus staining in the epithelium persisted. These studies show definitively that IL-5, eosinophils, or mast cells are not essential, but signaling through IL-4Ralpha is critically important in Th2 cell stimulation of mucus production. (+info)
A novel and highly divergent homolog of human eosinophil granule major basic protein.
(15/1614)
Eosinophils are important effector cells in defense against helminth infection and in allergic diseases. To identify novel eosinophil proteins, large scale sequencing of a cDNA library prepared from interleukin-5-stimulated umbilical cord precursor cells was performed, and the major genes expressed by maturing eosinophils were determined. This resulted in the identification of a cDNA with 64% identity to human prepro-major basic protein (hprepro-MBP). This cDNA was designated hprepro-MBP homolog (hprepro-MBPH). Interestingly, the calculated pI values for hMBPH and hMBP differed by >100-fold, with pI values of 8.7 and 11.4, respectively. Given this pronounced basicity difference, the homolog transcript's abundance (1.1%), and MBP's critical role in eosinophil biological activity, we further characterized the homolog. Reverse transcription-polymerase chain reaction detected transcription of hprepro-MBPH in bone marrow only, and this result was confirmed by analysis of a large cDNA data base (electronic Northern). hMBPH was isolated from human eosinophil granule lysates, and its identity was verified by amino acid sequencing and by mass spectrometry. Analyses of the biological activities showed that hMBPH had effects similar to hMBP in cell killing and neutrophil (superoxide anion production and interleukin-8 release) and basophil (histamine and leukotriene C4 release) stimulation assays, but usually with reduced potency. Overall, this novel homolog's unique physical properties indicated that the high net positive charge of hMBP is important but not essential for biological activity. (+info)
Simultaneous disruption of interleukin (IL)-4 and IL-13 defines individual roles in T helper cell type 2-mediated responses.
(16/1614)
Using a single vector targeting strategy, we have generated mice with a combined deficiency of interleukin (IL)-4 and IL-13 to clarify their roles in T helper type 2 (Th2) cell responses. Using immunological challenges normally characterized by a Th2-like response, we have compared the responses of the double-deficient mice with those generated by wild-type, IL-4-deficient, and IL-13-deficient mice. Using a pulmonary granuloma model, induced with Schistosoma mansoni eggs, we demonstrate that although eosinophil infiltration, immunoglobulin E, and IL-5 production are reduced in the IL-4-deficient mice and IL-13-deficient mice, they are abolished only in the combined absence of both cytokines. Furthermore, IL-4/13-deficient animals are severely impaired in their ability to expel the gastrointestinal nematode Nippostrongylus brasiliensis. Unexpectedly, N. brasiliensis-infected IL-4/13-deficient mice developed elevated IL-5 and eosinophilia, indicating that compensatory mechanisms exist for the expression of IL-5, although serum IgE remained undetectable. IL-4/13-deficient mice default to a Th1-like phenotype characterized by the expression of interferon gamma and the production of IgG2a and IgG2b. We conclude that IL-4 and IL-13 cooperate to initiate rapid Th2 cell-driven responses, and that although their functions overlap, they perform additive roles. (+info)